The present invention relates generally to RCA type electrical plug and jack connectors and, more particularly, to electrical plug and jack connectors configured to provide reduced relative movement when connected together and thereby reduce the likelihood of intermittent electrical discontinuity.
Plug connectors are well known for use in connecting, e.g., audio equipment. With RCA-type plugs, a ground sleeve or the like surrounds a central signal pin. One such plug is used for mono (single channel) transmission and two side-by-side plugs are used for stereo (two-channel) transmission. Generally, the mating contacts for the pins and sleeves with associated jack structures are smooth. Because of, e.g., resiliency and tolerances between the structures, the plugs are somewhat moveable within the jack and through wear and the like the movement increases. This often leads to intermittent contact and a resulting disturbance in the quality of the audio signal.
Accordingly, it is an object of the present invention to provide an RCA-type plug connector that can be easily manufactured and assembled, yet reliably achieves reduced relative movement when mated with a jack connector. The invention is particularly directed to an RCA audio signal connector for attachment to a coaxial audio cable having a central signal conductor and an outer ground conductor.
According to the invention, the connector has an elongated, substantially cylindrical base having front and back ends, a throughbore extending axially between the front and back ends, and a counterbore at the front end. A rigid, elongated, conductive signal core has a back end within the base and a front end extending from the base along the axis. A conductive spring member surrounds the core and extends along the core axis with a front end adjacent the front end of the core and a back end adjacent the back end of the core, the spring member including a plurality of radially outwardly bowed spring elements between the front and back ends. A substantially cylindrical ground sleeve has a back end situated in the counterbore at the front end of the base and rigidly engaging the base, and a front end that projects forward from the front end of the base. An insulating ring is situated within and rigidly engages the sleeve. The insulating ring also supports the core and the spring member, preferably by means of a front portion intimately molded over the back end of the core member and the back end of the spring member. The ring has a back portion including a bore coaxially aligned with the through bore of the base such that the audio cable is insertable from the back of the base. With the connector thus assembled, the front end of the core projects forward of the front end of the sleeve and the spring elements of the spring member extend along the core forward of the ring, while spaced radially inwardly of the sleeve.
Preferably, the sleeve engages the base by interference fit near the front end of the base, and the insulating ring engages the sleeve by interference fit forward of the engagement of the sleeve with the base. The engagement between the base and the sleeve can be in the form of a tab on the sleeve engaging a slot on the base, and likewise the engagement between the sleeve and the insulating ring can be by means of a tab on the ring engaging a slot on the sleeve.
The spring elements preferably surround the core forward of the front end of the sleeve. The core has an enlarged head at the front end, defining a front shoulder and the front portion of the spring member abuts the front shoulder, while the back end is supported by the insulating ring within the base.
If the core has a shoulder at the back end, the back end of the spring member abuts the shoulder, and the insulating ring is molded over the shoulder and the spring back end, this configuration prevents relative movement among the ring, the core, and the spring member.
A conductive ground contact connects the sleeve to the ground conductor of the cable and a conductive signal contact connects the core to the signal conductor of the cable, when the cable is inserted from the back of the base through the bore of the base into the bore in the ring. Ideally, the conductive signal contact is a pin extending from the back end of the core along the axis, for engaging the signal conductor on the cable. Preferably, the conductive ground contact is formed in part by a conductive base and in part by a conductive screw passing through the base into the throughbore where it can bear against the ground conductor of the cable.